Measurements of water uptake of maize roots: the key function of lateral roots
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Maize (Zea mays L.) is one of the most important crops worldwide. Despite several studies on maize roots, there is limited information on the function of different root types in extracting water from soils. Aim of this study was to investigate the location of water uptake in maize roots.
We used neutron radiography to image the spatial distribution of maize roots in soil and trace the transport of deuterated water (D2O) in soil and roots. Maize plants were grown in aluminum containers filled with a sandy soil that was kept homogeneously wet throughout the experiment. When the plants were 16 days old, we injected D2O into selected soil regions. The transport of D2O was simulated using a diffusion–convection numerical model. By fitting the observed D2O transport we quantified the diffusion coefficient and the water uptake of the different root segments.
The root architecture of a 16 day-old maize consisted of a primary root, 4–5 seminal roots and many lateral roots. Laterals emerged from the proximal 15 cm of the primary and seminal roots. During both day and night measurements, D2O entered more quickly into lateral roots than into primary and seminal roots. The quick transport of D2O into laterals was caused by the small radius of lateral roots. The diffusion coefficient of lateral roots (4.68 × 10−7 cm2 s−1) was similar to that of the distal unbranched segments of seminal roots (4.72 × 10−7 cm2 s−1) and higher than that of the proximal branched segments (1.42 × 10−7 cm2 s−1). Water uptake of lateral roots (1.64 × 10−5 cm s−1) was much higher than the uptake of seminal roots, which was 5.34 × 10−10 cm s−1 in the proximal branched segments and only 1.18 × 10−12 cm s−1 in the distal unbranched segments.
We conclude that the function of lateral roots is to absorb water from the soil, while the function of the primary and seminal roots is to axially transport water to the shoot.
KeywordsLateral roots Seminal roots Neutron radiography Root water uptake Deuterated water (D2O) Maize Radial and axial conductivity
The doctoral position of Mutez Ahmed was funded by the German Academic Exchange Service (DAAD). We are grateful to the staff at the ICON imaging station of the Paul Scherrer Institute (PSI), Villigen, Switzerland for their technical support during the measurements with neutron radiography. KWS is appreciated for providing Maize seeds. Finally, we would like to thank Claude Doussan for his comments on a former presentation of this study and two anonymous reviewers for the constructive comments on the former version of the manuscript.
- Brouwer R (1953) Water absorption by the roots of vicia faba at various transpiration strength: analysis of the uptake and the factors determining it. I.Google Scholar
- Carminati A (2012) A model of root water uptake coupled with rhizosphere dynamics. Vadose Zone J 11. doi: 10.2136/vzj2011.0106
- Hochholdinger F (2009) Handbook of Maize: Its Biology. In: Bennetzen JL, Hake SC (eds) The Maize Root System: Morphology, Anatomy, and Genetics. Springer, New York, pp 145–160Google Scholar
- Koebernick N, Weller U, Huber K, et al (2014) In situ visualization and quantification of three-dimensional root system architecture and growth using x-ray computed tomography. Vadose Zone J 13. doi: 10.2136/vzj2014.03.0024
- Matsushima U, Kardjilov N, Hilger A et al (2012) Application potential of cold neutron radiography in plant science research. J Appl Bot Food Qual 82:90–98Google Scholar
- Pohlmeier A, Javaux M, Vereecken H, et al (2013) Magnetic Resonance Imaging Techniques for Visualization of Root Growth and Root Water Uptake Processes. In: SSSA Special Publication. The Soil Science Society of America, Inc.Google Scholar
- Sierp H, Brewig A (1935) Quantitative untersuchungen über die wasserabsorptionszone der wurzeln. Jahrb Wiss Bot 82:99–122Google Scholar
- Sposito G (2013) Green water and global food security. Vadose Zone J 12. doi: 10.2136/vzj2013.02.0041
- Varney GT, Canny MJ (1993) Rates of water uptake into the mature root system of maize plants. New Phytol 775–786Google Scholar
- Zarebanadkouki M, Kim YX, Moradi AB, et al (2012) Quantification and modeling of local root water uptake using neutron radiography and deuterated water. Vadose Zone J 11. doi: 10.2136/vzj2011.0196
- Zarebanadkouki M, Kroener E, Kaestner A, Carminati A (2014) Visualization of root water uptake: Quantification of deuterated water transport in roots using neutron radiography and numerical modeling. Plant Physiol 114.243212. doi: 10.1104/pp.114.243212